Chain Drive Calculator

How it works

1. 1Enter the chain pitch (distance between roller centres), the tooth count on each sprocket, and the centre distance between sprocket shafts.
2. 2The calculator applies the standard chain-length formula — accounting for both straight and wrapped sections — to return the total chain length in your chosen unit system.
3. 3The link count is rounded up to the next even integer, since roller chains always require an even number of pitches for the master link to close correctly.

Use cases

• Sizing a replacement chain for a bicycle, motorcycle, or industrial conveyor without disassembling the drive.
• Designing a new power-transmission drive where centre distance and sprocket sizes are known but chain length must be determined.
• Checking whether an off-the-shelf standard-length chain will fit a given sprocket pair and centre distance.

Frequently asked questions

What is chain pitch?

Pitch is the distance between the centres of two adjacent rollers on the chain. Common roller-chain pitches follow ANSI standards: #25 (6.35 mm / ¼ in), #40 (12.7 mm / ½ in), #50 (15.875 mm / ⅝ in), and #60 (19.05 mm / ¾ in). Always match the chain pitch to the sprocket tooth profile.

Why must the chain have an even number of links?

A standard roller chain connects end-to-end with a master (connecting) link. Because inner and outer link plates alternate, an even number of pitches is needed so the two ends present matching plate types. An odd count requires a special offset link, which is weaker and should be avoided where possible.

How is the chain length calculated?

The formula is L = 2C + (N₁ + N₂)/2 + (N₂ − N₁)²/(4π²C), where C is the centre distance in pitches, N₁ is the small-sprocket tooth count, and N₂ is the large-sprocket tooth count. The result in pitches is multiplied by the pitch to give the physical length, with metric/imperial conversion handled automatically.